Crank case for an internal combustion engine or the like

ABSTRACT

A crank-case for an internal combustion engine comprising a flat supporting structure extending throughout the length of the crank-case and consisting of a single supporting plate consisting of one single for example integrally cast or rolled part forming a single continuous main beam made in one piece and receiving the fastening ends of the cylinder tie-bolts whereas the transverse partitions and longitudinal walls consist each one of a bottom portion and of a top portion in extension of one another and welded to said supporting plate above and below same, respectively, while being separated therefrom.

Unlted States Patent 1 1 [111 3,769,953

Kuhn Nov. 6, 1973 [54] CRANK CASE FOR AN INTERNAL 3,064,633 11/1962 Seifert et al. 123/195 S COMBUSTION ENGINE R THE LIKE 3,528,397 9/1970 Seifert 123/195 R [75] Inventor; Karl Walter Kuhn, FOREIGN PATENTS OR APPLICATIONS Saint-G rma y France 166,234 7 1921 Great Britain 123 55 vs Assignee: Sociee d,Etudes de Machines 754,554 11/1933 France 123/195 S Therrniques, Saint-Denis, France Prlmary ExammerWendell E. Burns Flled: y 26, 1971 Att0rney-Kenyon & Kenyon Reilly Carr & Chapin [211 App]. No.: 147,046

7 [57] ABSTRACT [30] Foreign Application Priority Data A crank-case for an internal combustion engine com- May 29 1970 France 7019788 prising a flat suPporting Structure extendmg hmughout Feb. 23 1971 France 7106105 the length 0f the crank-case and 8 a Single supporting plate consisting of one single for example 52 vs. C! 123 195 R integrally cast or rolled P forming a Single 51 1 Int. Cl F02f 7/00, F02f 1/10 0118 main beam made in 9119 Piece and receiving the [58] Field 61 Search 123 195 R, 195 s, telling ends of the cylinder tie-bolts Whereas the trans- 123/195 VS 195 VB 4 verse partitions and longitudinal walls consist each one of a bottom portion and of a top portion in extension [56] References Cited of one another and welded to said supporting plate above and below same, respectively, while being sepa- UNITED STATES PATENTS rated therefrom. R15,0l9 l/192l Landgraf.... 123/55 VS 1,720,510 7/1929 Chorlton 125/55 VB 14 Clairns,-10 Drawing Figures CRANK CASE FOR AN INTERNAL COMBUSTION ENGINE OR THE LIKE The present invention relates to a crank-case for an internal combustion engine in particular with one or two longitudinal rows of built-in cylinders as well as to the various applications and uses resulting therefrom and to the engines and machines fitted therewith.

There are already known crank-cases for internal combustion engines with a plurality of built-in bylinders arranged in particular either in line or in two longitudinal rows according to a V-shaped arrangement, of the type forming a possibly ribbed hollow box of combined construction that is forming an assembly composed of cast or forged elements and of metal sheets andv like rolled products connected together by welding. Such a structure often exhibits a configuration with pillars or legs comprising in particular transverse, vertical, spaced, intermediate and end partitions forming supporting webs for the crank-shaft bearings and welded for this purpose on forged yokes or the like, respectively, constituting the bearing cages. These transverse partitions are connected with each other by supporting plates madefrom cast steel and mutually juxtaposed in alignment along an intermediate partition level to form a supporting structure and comprising respective openingsadapted to accommodate the lower portions of the cylinder liners. In the case of an engine withV-shaped cylinders, each supporting plate has its direction corresponding to its largest dimension disposed transversely of the crank-case with a roof-like configuration forming an upward projecting dihedron having its edge directed longitudinally of the crankcase substantially in the longitudinal vertical centre plane thereof. Each supporting plate is then provided with a pair of transverse openings for example longitudinally offset or shifted with respect to each other and located in the faces, respectively, on either side of said central edge whereas in the case of an engine with inline cylinders, each plate is substantially flat and horizontal and comprises one single aforesaid opening. The assembly of the transverse partitions and of the supporting platesis welded on each side, respectively, on longitudinal metal sheets forming a pair of at least approximately vertical opposite side walls or faces of the crank-case between and to which are welded said transverse partitions and supporting plates. At the upper portion, a tablet-like metal sheet which is substantially flat and horizontal in the case of an engine with in-line cylinders or folded according to a roof-like configuration in the case of an engine with V-shaped cylinders is welded to the corresponding ends of the transverse partitions and of the longitudinal side walls. This metal sheet is formed with parallel circular openings which are coaxial with those of said supporting plates, which openings are adapted to accommodate the cylinder water jackets. The transverse partitions and longitudinal side walls thus extend substantially continuously throughout the height of the crank-case above and below the intervening cast supporting plates. The longitudinal walls extend substantially throughout the length of the crank-case and the transverse partitions also extend substantially continuously over the whole width of the crank-case. These transverse partitions are substantially flat in the case of an engine having inline cylinders whereas they are offset or shifted longitudinally with respect to each other by being bent twice in opposite directions along vertical folds in the case of an engine with V-shaped cylinders to make allowance for the longitudinal offset of staggering of the cylinders from one row to the other when such an offset is present. F inally in an engine with V-shaped cylinders the transverse partitions are in addition braced above the sup porting plates by longitudinal, vertical metal-sheet members substantially aligned above the central crest or ridge of the cast supporting plates extending throughout the height available between said supporting plates and the upper tablet-like metal sheet to form a central vertical longitudinal partition welded to the transverse partitions, to the supporting plates and to the upper tablet-like metal sheet. In such a known con struction, the assemblies are generally carried out by fillet welding with seams or the like.

Such a known construction offers several drawbacks. On the one hand, the transmission of the force fluxes and of alternating stresses from said supporting plates to the transverse partitions and therefrom to the bearings is unequally distributed in view of the discontinuities existing between the juxtaposed supporting plates and owing to the fact that combined tensile and shear stresses are present in the fillet welds. On the other hand, the fillet welds are of a random reliability in view of the differencies between cross-sectional areas generally exhibited by the parts to be connected at an angle and the quality control of the fillet welds which in particular transmit the cylinder stresses to the bearings is difficult to carry out owing to their configuration making their access inconvenient. Finally the fillet welding step is relatively difficult to carry out at least on some portions of the crank-case owing to the fact that the joints to be welded are not very accessible. Such a fillet welded construction also exhibits a relatively large number of welded joints which is not appropriate in view of the pressure of concentrated residual stresses and from the standpoint of the cost price.

The main object of the invention is to remove said drawbacks and difficulties by providing a crank-case composed of a relatively reduced number of parts and elements assembled by welding. To this end, the crankcase according to the invention is characterized in that said, supporting structure is a single supporting plate consisting of one single integral for example cast or rolled part forming a single continuous main beam made in one piece of material and receiving the anchoring of the cylinder tie-bolts whereas said transverse partitions and longitudinal walls consist each one of a bottom portion and of a top portion substantially in extension of each other and which are welded to said supporting plate below and above the latter, respectively, while being separated thereby, said upper tablet-like plate or metal sheet being welded to said top portions.

According to a further characterizing feature of the invention in the case of an engine with a pair of rows of V-shaped cylinders with a roof-like supporting plate forming an upward projecting dihedron with a central longitudinal crest edge and with a central longitudinal,

partition welded beween said supporting plate and said upper tablet-like plate above said crest edge, said longitudinal partition consists of one single continuous metal sheet extending preferably substantially over the whole length of the crank-case whereas the top portion of each aforesaid transverse partition consists of a pair of bracing'elements fillet welded at a preferably substantially right angle to said longitudinal partition on either side thereof and to each aforesaid side wall between the latter and said longitudinal partition.

According to still another characterizing feature of the invention, said supporting plate comprises on each one of its opposite respective lower and upper faces, at least approximately vertical projecting ribs or ridges forming scarfs of material integrally cast for buttwelded assembly with said partitions and walls.

According to still a further characterizing feature of the invention and in the case of an engine with removable lower body portions of the crank-shaft bearings which are detachable from below and adapted to be assembled to yoke-shaped bearing cages, respectively, integral with the respective transverse partitions, said bottom portion of each transverse partition is made in one single cast integral piece together with its associated yoke.

These various arrangements offer in particular in combination with each other considerable advantages. As a matter of fact the transmission of alternating stresses from the supporting plate to the transverse partitions and therefrom to the crank-shaft bearings is better distributed and more uniform since it is distributed through the continuous beam formed of the integral supporting plate and through the butt-welds which are subject to tensile stresses only. Moreover the welds being of the butt-weld type with total penetration are of a better quality hence of a higher reliability since the cross-sections to be connected together and which consist generally of said integrally cast stand-by ridge and of a partition or wall metal sheet are of approximately or substantially the same size. The control of the welds and in particular of those which are transmitting the cylinder stresses to the bearings is easier to carry out in particular by radiography or by ultra-sounds or by magnetoscopy and finally the welding steps are easier to be carried out since the joints to be welded are more accessible and the welds may be carried out at least in part by automatic machines. Moreover there are much less welds, so that any possible inner stresses are less numerous and less high. Such a crank-case is of substantial rigidity or mechanical strength and of a relatively simple configuration hence of economical manufacture.

The invention will be better understood and further objects, characterizing features, details and advantages thereof will appear more clearly as the following explanatory description proceeds with reference to the diagrammatic accompanying drawings given by way of example only illustrating several forms of embodiment of the invention and wherein:

FIG. 1 shows an elevational view in cross-section taken upon the broken line I-l of FIG. 2, of a crankcase of an internal combustion engine in particular of the Diesel type with a pair of rows of radially arranged V-shaped cylinders with mounted crank-shaft and bearings FIG. 2 is a fragmentary view in cross-section taken upon the broken line II-II of FIG. 1 showing in particular the top of the integral supporting plate made from cast steel together with the top portions of the partitions and walls FIG. 3 is a fragmentary view drawn to a larger scale in horizontal section taken upon the line III-III of FIG. I, particularly showing the structure of the bottom portion of one transverse partition FIG. 4 is a fragmentary view at an enlarged scale in partial section taken upon the line IVIV of FIG. I, particularly showing the welded assembly of the walls and partitions on the connecting ridges integrally cast with the supporting plate made in one piece from cast steel FIG. 5 is a enlarged view of the encircled detail V of FIG. 1 showing one portion of the central region of the top of the supporting plate integrally made from cast steel;

FIG. 6 is a view similar to the preceding one and showing the encircled detail VI of FIG. 1 in the lateral edge region of the supporting plate made in one piece from cast steel;

FIG. 7 shows a separate top view of said supporting plate according to a form of embodiment carried out by casting in two cast parts connected together by a transverse weld FIG. 8 is an end side view, seen from the left-hand side, of the supporting plate shown on FIG. 7

FIG. 9 is an enlarged fragmentary view in crosssection taken upon the line IX-lX of FIG. 7 of the area assembled by welding and FIG. 10 is an enlarged fragmentary cross-sectional view of the upper portion of an engine crank-case showing an alternative embodiment of the supporting plate made in two parts connected together by a central longitudinal weld.

According to the examplary embodiment shown on FIG. 1, the crank-case shown therein is intended for use with a Diesel engine with V-shaped cylinders which are for example longitudinally offset or shifted with respect to each other from one row to the other and the longitudinal central planes of which passing through the cylinder axes of both cylinder rows, respectively, define for example therebetween a 45 dihedral angle. On FIG. 1, the base plate forming in particular the oil sump has not been shown. This crank case essentially comprises the integral supporting plate made in one piece from for example cast or rolled steel and generally denoted by the reference numeral 1 and extending continuously substantially throughout the length of the crank-case. This supporting plate assumes substantially the shape of a roof defining a dihedral angle the top edge or crest line of which is located in the central longitudinal vertical plane of the crank-case. This supporting plate comprises in each face of its dihedron openings 2 adapted to accommodate the lower portions of the cylinder liners and the axes of which are mutually offset or shifted with respect to each other in the longitudinal direction from one cylinder row to the other according to FIG. 2 which particularly shows the end portion of the crank-case located on the side opposite to the timing system or coupling. On its top face the supporting plate comprises blind tapped holes 3 (FIGS. 2, 5 and 6) arranged about each opening 2 and adapted to accommodate the screw-threaded connection of the cylinder tie-bolts 4 securing the water jackets 5 and the liners 6 of the cylinders as well as the cylinder heads 7 to the crank-case according to the sketch in dashdotted lines of FIG. 1. The supporting plate 1 comprises projecting connecting ridges or ribs for buttwelded assembly edge-to-edge of the supporting plate with other structural elements of the crank-case and directly integrally cast in one piece with said supporting plate. These connecting ridges or welding assembly scarfs are in the shape of continuous ribs. The bottom face or the supporting plate 1 thus exhibits a pair of continuous parallel longitudinal substantially vertical ribs 8 extending along each one of both longitudinal opposite edges, respectively, of the supporting plate and transverse, spaced, substantially parallel and vertical ribs 9 extending continuously throughout the width of the supporting plate between the longitudinal ribs 8 and separating transverse pairs of openings 2, respectively. All of these ribs are substantially flat and straight so that the transverse ribs 9 are oblique or inclined with respect to the longitudinal direction of the crank-case for making allowance for the possible mutual offset or staggering of the openings 2 in the longitudinal directionof a longitudinal row of openings with respect to each other. Similarly the top face of the supporting plate 1 comprises a pair of continuous longitudinal lateral substantially straight ribs 10 extending over the whole length of the crank case, respectively, along both opposite longitudinal edges thereof while being directed obliquely upwards so as to diverge sidewise outwards. The top face of the supporting plate 1 comprises in addition on the one hand a longitudinal, central, substantially vertical, straight rib 11 extending continuously along the longitudinal, central crest line of the supporting plate and substantially parallel'and vertical, spaced, straight, transverse ribs 12 extending on each face of the dihedron formed by the supporting plate, respectively, throughout the width thereof between one longitudinal side rib 10 and the cental longitudinal rib 11 substantially at right angles thereto so as to separate the successive openings 2, respectively, in each face, whereby these transverse ribs 12 are longitudinally offset from one face to the other according to the corresponding offsets of the openings 2 of these respective faces.

Onto the continuous longitudinal ribs 10 and 11 of the top face of the supporting plate are respectively butt-welded three substantially flat continuous longitudinal metal sheets extending substantially through the length of the crank-case and comprising a pair of lateral metal sheets 13 forming sidewalls or faces of the the adjacent transverse partition to form a box adapted to accommodate the distribution or timing system.

Onto the upper longitudinal and transverse metal sheets 13 to 17 is welded through fillet welds an upper metal sheet 18 folded to form a dihedron so as to assume substantially the shape of a roof corresponding to that of the supporting plate 1 while extending in paralcrank case extending along its opposite longitudinal edges, respectively, while being inclined respectively for being aligned with the ribs 10 in extension thereof and a substantially vertical,central metal sheet 14 forming a longitudinal partition extending also nearly over the whole length of the crank-case. Onto the transverse ribs 12 of the top face of the supporting plate 1 are respectively butt-welded substantially flat and vertical transverse metal sheets 15 forming upper transverse partitions, respectively, aligned with their associated ribs in extension thereof, so that they are also offset in the longitudinal direction from one face to the other of the supporting plate 1 according to FIG. 2. These metal sheets of the upper transverse partitions 15 are respectively fillet welded onto the longitudinal lateral and central metal sheets 13 and 14. At each end of the crank-case the longitudinal metal sheets 13 and 14 are limited by a single transverse metal sheet 16 twice bent in opposite directions and extending over the whole width of the crank-case and onto which the longitudinal metal sheets 13 and 14 are secured by fillet welds (FIG. 2). As shown on FlG. 2, each end of the crankcase is limited or terminated by a substantially flat and vertical end wall metal sheet 17. On the coupling side, this end metal sheet is spaced to a larger extent from lel relation thereto and forming an upper tablet. In each face of the dihedron formed by the metal sheet 18 are provided round openings 19 corresponding to the openings 2, respectively, of the supporting plate while being arranged in parallel and coaxial relation thereto to accommodate the water jackets 5 of the cylinders. The upper portion of the crank-case located above the supporting plate 1 is thus divided into adjacent compartments each one assigned to one cylinder of the engme.

Onto the longitudinal ribs 8 of the bottom face of the supporting plate are butt-welded a pair of substantially flat, vertical, parallel, continuous,longitudinal metal sheets 20, respectively, aligned with the ribs 8, respectively, in extension thereof and forming the lower side walls or faces of the crank-case. These metal sheets 20 also extend nearly over the whole length of the crankcase. Onto each transverse rib 9 of the bottom face of the supporting plate 1 is butt-welded a transverse partition made from cast steel 21 and assembled in edge-toedge relationship in alignment with the associated rib 9 in extension thereof. Each transverse partition 21 extends over the whole width of the crank-case between the lateral longitudinal metal sheets 20 and is fillet welded onto the latter. At least each intermediate transverse partition 21 comprises a substantially flat solid web 22 and a central recess 23 at least approximatively in the shape of an inverted U opening downwards and defined by a thickened bead-like or bulb-like portion 24 forming a yoke-shaped crank-shaft bearing cage integrally cast in one piece with the web 22. As shown in particular by FIG. 3, the bearing cage or yoke 24 has a substantially flat and vertical configuration directed at right angles to the horizontal crank-shaft axis 25 hence to the longitudinal side walls 20 of the crankcase whereas the web 22 is disposed obliquely with respect to the plane of the bearing cage 24 hence with respect to the crank-shaft axis 25 so as to follow the obliqueness of the associated transverse rib 9 of the supporting plate between two adjacent,transverse,- successive pairs of cylinders to match the possible longitudinal offset of the latter from one cylinder row to the other. This offers the advantage of removing the double folding in opposite directions of the transverse partitions of the crank-cases known from the prior state of the art. The transverse partitions 21 therefore define together with the longitudinal side walls 20 successive adjacent compartments opening downwards and corresponding each one to one transverse pair of cylinders. Such a configuration enables to mount the crank-shaft 26 within the bearing cage 24 so that it may be easily removable from below. Through each longitudinal lateral metal sheet 20 extends at least one for example substantially circular inspection hole 27 opening into one aforesaid compartment and enabling the inspection and disassembling of the pivotal connections, couplings and connecting-rod bearings. These holes are normally closed by removable doors or covers not shown.

At each transverse partition 21, the crank-shaft 26 which in this example is removable from the bottom, is mounted with its journals in suitable bearing bushes and held in the corresponding bearing yoke 24 by means of a removable bearing body portion 28 detachable from the bottom which is secured by a pair of tiebolts 29 screw-threaded within suitable tapped holes of the bearing cage 24 and receiving corresponding nuts 30 at their respective free lower ends. Each bearing body portion 28 is moreover held laterally on each side by a transverse substantially horizontal screw 31 extending through a smooth hole provided in a corresponding cast boss of the partition 21 for being screwthreaded into a tapped blind hole of the bearing body portion 28.

Two longitudinal substantially horizontal side base flanges 32 are welded to the bottom of the longitudinal walls and to the transverse partitions 21, respectively, on each side. These flanges extend substantially continuously over the whole length of the crank-case and serve to secure the crank-case onto the base plate, a pedastal or like supporting platform known per se.

Although the exemplary form of embodiment shown is concerned with an engine with V-shaped cylinders which are longitudinally offset from one row to the other the invention is also applicable to the case where the cylinders are not offset or shifted that is wherein the axes of two cylinders of a transverse pair of cylinders are meeeting in a same plane extending at right angles to the crank-shaft of the engine. In this latter case the web of each transverse partition is no longer oblique but also perpendicular to the engine crank-shaft. Likewise the stand-by ridges for butt-welding onto the supporting plate could possibly be omitted and the buttwelding could be replaced by a fillet welding in this case the cast supporting plate could be replaced by a supporting plate made from sheet metal or a like rolled product.

Moreover, the crank-shaft could also be mounted so as to be removable from above while still using a bearing body portion removable from below. In such an arrangement which could for instance be of the type according to the U.S. Pat. No. 3,520,045 issued on Oct. 3, 1967 in the name of the Applicant, the bearing yoke within the transverse partition is more deeply recessed upwards to allow the accommodation of an upper bearing cap removable from above and clamped against the bearing body portion by a set screw engaging the yoke and selectively adjustable to the desired clamping pressure by means of a hydraulic actuator incorporated into the bearing cap. In the case of a crank-case provided for an engine with a single row ofin-line cylinders, it is obvious that the supporting plate 1 will be substantially flat and horizontal and the transverse partitions will have their webs extending substantially at rights angles to the crank-shaft axis.

The object of the forms of embodiments according to FIGS. 7 through 10 is to further extend and generalize the concept of an integral part formed by said supporting plate so that it is not limited exclusively to parts made entirely and exclusively in one piece of material. For this purpose said supporting plate consists of several elements directly butt-welded to each other. In the case of an engine crank-case with a pair of longitudinal rows of built-in cylinders mutually offset from one row to the other and with an integral rolled supporting plate substantially of roof-like configuration having the shape of an upward projecting dihedron with a longitudinal central crest edge, said supporting plate consists of at least one element made of a metal sheet bent or folded along said longitudinal edge.

Such an arrangement offers the advantage of increasing and diversifying the possibilities and processes of manufacture of the supporting plate thereby showing a usefulness from the economical standpoint towards cutting down the manufacturing cost price of the crank-case.

According to the illustrative form of embodiment shown on FIGS. 7 to 9, the supporting plate 101 is for use on an internal combustion engine with two rows of V-shaped cylinders and therefore assumes a roof-like shape forming an upward projecting dihedron with a longitudinal central crest edge. This integral supporting plate 101 is made entirely by a casting process together with its longitudinal and transverse ribs 102 forming ridges or scarfs for welded assembly with the partitions and walls of the crank-case and consists of at least two cast elements 103 and 104, respectively, juxtaposed in aligned registering relationship in the longitudinal direction and connected together by a transverse butt- Weld 105 preferably of straight configuration and extending substantially at right angles to the longitudinal direction of the supporting plate. This welded joint is shown in greater detail in cross-section on FIG. 9.

The supporting plate may of course consist of more than two elements and each transverse weld seam 105 extends for example in the middle between the transverse parallel diametral planes 106a, 1070, respectively, of two transversely corresponding openings 106, 107 longitudinally offset mutually from one row of openings to the other and which are adapted to accommodate two cylinders, respectively, belonging each one to one row.

According to the alternative embodiment of FIG. 10, the supporting plate 109 consists of at least two elongated elements 109, 110 transversely put together side by side in engaging relationship along a longitudinal edge and connected together edge-to-edge by a longitudinal preferably substantially straight weld seam 111 which in the case of an engine with two rows of mutually ofiset V-shaped cylinders desirably extends along the longitudinal edge of the roof-like salient dihedron formed by the supporting plate 108. In this form of embodiment said ribs 102 may be omitted so that the various partitions and walls of the crank-case adapted to be secured to this supporting plate are directly filletwelded onto the latter.

The elements 103, 104 or 109, 110 of the supporting plate 101 or 108 may be made from a rolled metal sheet instead of being cast. In this form of embodiment made of rolled sheet metal, the supporting plate will generally be devoid at least of transverse ribs 102 while the central longitudinal rib 102 may possibly be also made integral with the same piece of material through a rolling process.

The embodiments with a cast or rolled structure stated hereinabove are of course also applicable to the case of a supporting plate of an engine crank-case with a single longitudinal row of cylinders so that the supporting plate will then be generally of flat configuration.

Moreover in an engine with two rows of V-shaped cylinders having their axes transversely aligned by pairs from one row to the other with a roof-shaped support- Q ing plate forming an upward projecting dihedron with a central longitudinal crest edge, each weld seam will preferably extend along the diametral transversal plane common to a transverse pair of cylinders.

Finally according to a further alternative embodiment of modification not shown, said supporting plate could consist of one single rolled metal sheet made integrally from one piece of material. in the case of a dihedral supporting plate 108 such as shown on FIG. 10, this supporting plate would then also consist of a rolled metal sheet folded or bent along the central, vertical,

longitudinal plane passing through the crest edge of the v dihedron that is at the location of the weld seam 111 of FIG. Ml. Alternatively the supporting plate may consist of several elements made from folded metal sheet transversely welded to each other.

It should be understood that the invention is not at all limited to the forms of embodiments described and shown herein which have been given by way of example only. in particular it comprises all the means described as well as their combinations if they are carried out according to the gist and scope of the invention as defined in the appended claims.

What is claimed is i 1. A crank-case for an internal combustion engine with at least one longitudinal row of built-in cylinders, held by tie-bolts, said crank-case forming a welded hollow box consistingof one-piece elements and of metal sheets and comprising a substantially flat supporting structure generally directed horizontally and extending substantially throughout the length of the crank-case and formed with openings accommodating the lower portions of the cylinder liners, vertical, spaced, intermediate and end transverse partitions forming supporting webs for the crank-shaft-bearings, two longitudinal at least approximatively vertical opposite walls forming the side faces and a tablet-like upper plate with parallel openings arranged in coaxial relation to those of said supporting plate for accommodating the cylinder water jackets,wherein the improvement consists in that said supporting structure is a single supporting plate consisting of one single integral part forming a single continuous'main beam made in one piece and receiving the fastening ends of the cylinder tie-bolts whereas the transverse partitions and longitudinal walls consist each one of a bottom portion and of a top portion substantially in extension of one another and which are welded to said supporting plate above and below same, respectively, while being separated therefrom, said tablet-like plate being welded onto said top portions.

2. A crank-case according to claim 1, with two rows of V-shaped cylinders with a roof-shaped supporting plate forming an upward projecting dihedron with a central, longitudinal crest edge and with a central longitudinal partition welded between said supporting plate and said tablet-like upper plate above said crest edge, wherein said longitudinal partition consists of one single continuous metal sheet whereas the top portion of each aforesaid transverse partition consists of two bracing elements fillet welded, respectively, at a substantially right angle onto said longitudinal partition on each side thereof and onto each aforesaid side wall between the latter and said longitudinal partition.

3. A crank-case according to claim 1, wherein said supporting plate comprises on each one of its respective upper and lower opposite faces at least approximatively vertical projecting ribs made integral for buttwelded assembly edge-to-edge with said partitions and walls. i

4. A crank-case according to claim 1, with removable lower crank-shaft bearing body portions detachable from below and connectable with yoke-like bearing cages, respectively, integral with respective transverse partitions, wherein said lower portion of each transverse partition is made from one single piece integral with its associated yoke.

5. A crank-case according to claim 1, for two rows of V-shaped cylinders longitudinally offset from one row to the other, wherein the web of. at least each aforesaid intermediate transverse partition is substantially flat and arranged obliquely with respect to the plane of the associated bearing between two adjacent transverse cylinder walls.

6. A crank-case according to claim 1, at least the intermediate transverse partitions of which comprise each one underneath said supporting plate an inverted U-shaped recess opening downwards, comprising a pair of longitudinal side base flanges welded beneath said longitudinal side walls and beneath said partitions, respectively, on each side for attachment onto a base plate.

7. A crank-case according to claim 1, wherein said supporting plate consists of several elements directly welded together edge-to-edge.

8. A crank-case according to claim 7, wherein said supporting plate consists of at least two elements juxtaposed in aligned relationship in the longitudinal direction and connected together by a straight transverse weld extending substantially at right angles to the longitudinal direction of said supporting plate.

9. A crank-case according to claim 8, for an engine with two rows of mutually offset V-shaped cylinders with a roof-shaped supporting plate forming an upward projecting dihedron with a longitudinal central crest edge, wherein each aforesaid transverse weld extends for example in the middle between the parallel transverse diametral planes of two aforesaid transversely corresponding openings which are longitudinally offset mutually with respect to each other.

' 10. A crank-case according to claim 8, for an engine with two rows of V-shaped cylinders with axes transversely aligned by pairs from one row to the other and having a roof-shaped supporting plate forming an upward projecting dihedron with a longitudinal central crest edge, wherein each weld seam extends along a diametral transverse plane common to a transverse pair of cylinders.

11. A crank-case according to claim 7, wherein said supporting plate consists of at least two elements transversely put together laterally and connected together by a substantiallystraight longitudinal weld seam.

12. A crank-case according to claim 1 1, for an engine with two rows of mutually offset V-shaped cylinders with a roof-shaped supporting plate forming an upward projecting dihedron with a longitudinal central crest edge, wherein said supporting p'late consists of two elements welded to each other along said longitudinal edge.

13. A crank-case for an internal combustion engine with two longitudinal rows of mutually offset built-in cylinders and comprising a longitudinal supporting plate made from rolled sheet metal stock, extending substantially continuously the full length of said crankcase with a roof-like configuration forming an upward cated separate element made from a a metal sheet bent along said longitudinal edge and welded to said crankcase.

14. A crank-case according to claim 13, wherein said supporting plate consists of several aforesaid elements made from a bent metal sheet and transversely welded to each other. 

1. A crank-case for an internal combustion engine with at least one longitudinal row of built-in cylinders, held by tie-bolts, said crank-case forming a welded hollow box consisting of onepiece elements and of metal sheets and comprising a substantially flat supporting structure generally directed horizontally and extending substantially throughout the length of the crank-case and formed with openings accommodating the lower portions of the cylinder liners, vertical, spaced, intermediate and end transverse partitions forming supporting webs for the crank-shaft bearings, two longitudinal at least approximatively vertical opposite walls forming the side faces and a tablet-like upper plate with parallel openings arranged in coaxial relation to those of said supporting plate for accommodating the cylinder water jackets, wherein the improvement consists in that said supporting structure is a single supporting plate consisting of one single integral part forming a single continuous main beam made in one piece and receiving the fastening ends of the cylinder tie-bolts whereas the transverse partitions and longitudinal walls consist each one of a bottom portion and of a top portion substantially in extension of one another and which are welded to said supporting plate above and below same, respectively, while being separated therefrom, said tablet-like plate being welded onto said top portions.
 2. A crank-case according to claim 1, with two rows of V-shaped cylinders with a roof-shaped supporting plate forming an uPward projecting dihedron with a central longitudinal crest edge and with a central longitudinal partition welded between said supporting plate and said tablet-like upper plate above said crest edge, wherein said longitudinal partition consists of one single continuous metal sheet whereas the top portion of each aforesaid transverse partition consists of two bracing elements fillet welded, respectively, at a substantially right angle onto said longitudinal partition on each side thereof and onto each aforesaid side wall between the latter and said longitudinal partition.
 3. A crank-case according to claim 1, wherein said supporting plate comprises on each one of its respective upper and lower opposite faces at least approximatively vertical projecting ribs made integral for butt-welded assembly edge-to-edge with said partitions and walls.
 4. A crank-case according to claim 1, with removable lower crank-shaft bearing body portions detachable from below and connectable with yoke-like bearing cages, respectively, integral with respective transverse partitions, wherein said lower portion of each transverse partition is made from one single piece integral with its associated yoke.
 5. A crank-case according to claim 1, for two rows of V-shaped cylinders longitudinally offset from one row to the other, wherein the web of at least each aforesaid intermediate transverse partition is substantially flat and arranged obliquely with respect to the plane of the associated bearing between two adjacent transverse cylinder walls.
 6. A crank-case according to claim 1, at least the intermediate transverse partitions of which comprise each one underneath said supporting plate an inverted U-shaped recess opening downwards, comprising a pair of longitudinal side base flanges welded beneath said longitudinal side walls and beneath said partitions, respectively, on each side for attachment onto a base plate.
 7. A crank-case according to claim 1, wherein said supporting plate consists of several elements directly welded together edge-to-edge.
 8. A crank-case according to claim 7, wherein said supporting plate consists of at least two elements juxtaposed in aligned relationship in the longitudinal direction and connected together by a straight transverse weld extending substantially at right angles to the longitudinal direction of said supporting plate.
 9. A crank-case according to claim 8, for an engine with two rows of mutually offset V-shaped cylinders with a roof-shaped supporting plate forming an upward projecting dihedron with a longitudinal central crest edge, wherein each aforesaid transverse weld extends for example in the middle between the parallel transverse diametral planes of two aforesaid transversely corresponding openings which are longitudinally offset mutually with respect to each other.
 10. A crank-case according to claim 8, for an engine with two rows of V-shaped cylinders with axes transversely aligned by pairs from one row to the other and having a roof-shaped supporting plate forming an upward projecting dihedron with a longitudinal central crest edge, wherein each weld seam extends along a diametral transverse plane common to a transverse pair of cylinders.
 11. A crank-case according to claim 7, wherein said supporting plate consists of at least two elements transversely put together laterally and connected together by a substantially straight longitudinal weld seam.
 12. A crank-case according to claim 11, for an engine with two rows of mutually offset V-shaped cylinders with a roof-shaped supporting plate forming an upward projecting dihedron with a longitudinal central crest edge, wherein said supporting plate consists of two elements welded to each other along said longitudinal edge.
 13. A crank-case for an internal combustion engine with two longitudinal rows of mutually offset built-in cylinders and comprising a longitudinal supporting plate made from rolled sheet metal stock, extending substantially continuously the full length of said crank-case with a roof-like configuration forming an upward projecting dihedron with a longitudinal crest edge for accomodating the lower portion of the cylinder liners within corresponding openings and for receiving the fastening ends of the cylinder tie-bolts, and a tablet-like upper plate with parallel openings arranged in coaxial relation to those of said longitudinal supporting plate for accomodating the cylinder water jackets, wherein said supporting plate consists of at least one prefabricated separate element made from a a metal sheet bent along said longitudinal edge and welded to said crank-case.
 14. A crank-case according to claim 13, wherein said supporting plate consists of several aforesaid elements made from a bent metal sheet and transversely welded to each other. 